The present invention relates generally to the distribution of two-phase fluids through pipeline networks comprising a header or manifold which supplies the fluid to a plurality of branch lines. More particularly, the invention relates to an apparatus which mixes, stratifies and divides a flowing two-phase fluid in such manner that each branch of a pipeline network will receive a quantity of the two-phase fluid having a gas-to-liquid ratio (GLR) which is substantially the same as the gas-liquid ratio of the source of the two-phase fluid.
There are many instances in which it is desired to distribute a mixture of a gas and a liquid to multiple end users or points of use from a single source of generation of the two-phase fluid. Such applications would include, for example, oil field pipelines, refinery networks, gas distribution lines carrying small amounts of condensate, and oil field steam injection pipeline networks carrying steam of less than 100% quality. Pipeline networks commonly use standard side branch pipe Tees to accomplish the splitting of a fraction of the flowing two-phase fluid out of the manifold or header into a branch line. It has long been known that the GLR of a two-phase fluid usually changes during splitting through such Tees because the liquid and gas phases tend to split in different proportions. Thus, in some pipeline networks as the amount of gas phase of the two-phase fluid entering the side branch of the Tee exceeds about 15% of the input gas phase a disproportionately greater portion of the liquid phase of the input fluid is diverted into the side branch of the Tee fitting.
One prior art approach to the problem involves a modification of the geometry of the pipeline network such that each Tee is oriented in a "dead end split" manner wherein the side arm, i.e. the stem of the Tee, comprises the upstream end of the Tee junction while the two coaxial arms of the head of the Tee comprise the split downstream ends of the junction. In this case, when 15% to 85% of the gas enters one of the two downstream branches, the liquid stream splits in substantially the same proportion as the gas, giving the same GLR downstream and upstream. Outside this range, however, almost all liquid enters the branch receiving most of the gas. A very great disadvantage of this dead end split Tee arrangement is that it yields a geometry of pipeline network utilizing excessive lineal feet of piping as contrasted to a geometry of pipeline network wherein a single trunk distribution line header supplies relatively short branch feeder lines in an arrangement wherein each branch line is connected to the stem of a Tee fitting while the head of the Tee is joined as an integral straight-through section of the single trunk distribution line.
In another prior art approach a pipeline network has been devised utilizing Wye fittings arranged such that the upstream end of the fitting comprises the stem of the Wye and a so-called motionless or static mixer is positioned immediately upstream of the stem of the Wye. Additionally, the stem of the Wye is fitted with a blade member for immediately splitting the two-phase fluid from the motionless mixer into two separate streams that pass through the divergent output legs of the Wye fitting. However, as in the case of the network utilizing dead end split Tees, this latter approach also yields a relatively expensive geometry of pipeline network. Additionally, notwithstanding the combination of a static mixer with a divider wall, it has been found that this arrangement does not provide equal quality distribution or splitting of the two-phase fluid over a useful range.